This invention relates to the placement of labels onto plastic containers, and in particular it relates to apparatus for transferring labels from a label magazine into the mold cavity prior to formation of the container, such that the label can be attached to the container at the time of the blow molding of the container.
Viewed in its entirety, the containerization process involves forming the plastic containers, applying a label to the plastic containers and filling the containers with the product. Heretofore, the general practice has been to apply the labels to the bottles in the course of a separate step performed at some time subsequent to the formation of the bottles.
This conventional technique suffers from several disadvantages. Firstly, there is the apparent economic disadvantage associated with the machine, labor and overhead costs required to establish and operate a label applying step subsequent to the bottle formation step. Another economic disadvantage is that after being formed, the bottles must continue to be processed individually throughout the labeling and/or filling steps. In contrast thereto, if the labels are already present on the bottles at the end of the blow molding step, the bottles may immediately be grouped and delivered to filling stations designed to fill the bottles in groups rather than individually.
The container industry has recognized that the above described disadvantages can be eliminated if the labels are delivered into the open mold cavity to be applied to the bottles during the molding process. Previous arrangements are shown, for example, in the Dickinson U.S. Pat. No. 3,324,508, the Borkmann U.S. Pat. No. 3,292,209, and the two U.S. Hellmer U.S. Pat. Nos. 4,355,967 and 4,359,314.
While these prior patents do recognize the basic concept of applying labels into an open mold, the structures shown therein suffer from certain disadvantages which limit their applicability. For example, Dickinson shows a complex arrangement which deals primarily with the relatively difficult task of removing labels from a roll rather than a magazine; and this patent, unlike the present invention, does not address the more delicate problem of properly placing the label into the open mold cavity. For example, Dickinson relies upon static electricity which is more difficult to control than pneumatic forces. Also, when fully analyzed, the movements of the transfer arms into the open mold cavity undergo a complex, non linear motion which is not conducive to the accurate positioning of the labels within the open mold cavity. Borkmann is similar to Dickinson in that it relates to the transfer of labels from a roll rather than from a magazine, and like Dickinson, Borkmann is primarily concerned with the difficult task of removing labels from a roll. Also like Dickinson, Borkmann shows and describes a relatively complex mechanical movement which does not lend itself to accurate and proper positioning of the labels into the open mold cavities. Specifically, in each of Dickinson and Borkmann the mechanical movements of the transfer arms in the vicinity of the open mold cavity include transverse components at the moment of transfer of the label from the transfer arm to the mold cavity, which component would tend to "scuff" the label as it is transfered to the mold cavity, thereby possibly damaging the label and minimizing the ability to perfectly position the label within the mold cavity.
The two patents to Hellmer are more relevant than Dickinson and Borkmann to the extent that they relate to the concept of transferring labels from a stack thereof in a label magazine rather than from a roll. However, these patents have other limitations. Firstly, it is apparent that these structures are relatively complex and it is believed would also suffer from the same "scuffing" problem discussed above with respect to Dickinson and Borkmann.
However, the Hellmer patents have another disadvantage in that they are limited to only certain types of blow molding machines. Commonly used blow molding machines include the "shuttle" and "slide" types. These types of machines are characterized by the fact that all of the procedural steps including introducing the preform, known as a parison, closing the mold cavities, blowing the parison into a container, opening the mold cavities and removing the formed container are carried out at a single or possibly two different stations. With all of these steps being performed at a single or two stations, there are problems which must be overcome concerning the mounting and arranging of an additional apparatus, in this case a label transfer apparatus, so as not to interfere with the mechanisms required for the other steps. There are other types of blow molding machines known as the "merry go round" or "ferris wheel" types wherein the mold halves travel to a large number of different stations, generally with a single step being preformed at each station. These machines provide far greater flexibility in the mounting and arranging of any specific apparatus. For example, the designer can simply provide an open station at which to mount a label transfering apparatus without having to concern himself with the closing of the blow mold or any other steps being performed at that station. In this context, the Hellmer patents suffer from the disadvantage that they are applicable, as shown, to the ferris wheel or merry go round types, but are not applicable to the shuttle or slide types. Movement of the mold halves into the vicinity of the label transfer apparatus, via a cam mechanism causes a rod to move against spring tension to carry a label from the magazine into the mold cavity. No external power is required for this movement. It is apparent that this mechanism could not be used with a shuttle or slide type of blow mold apparatus since this transfer apparatus has no means to remove the transfer arm from the space between the mold cavities other than by movement of the mold cavities away from the transfer apparatus. Hence, if utilized in a shuttle or slide type, the transfer arms would become crushed when the mold halves were pressed together for the blow molding step.
Copending application Ser. No. 524,193 filed Aug. 18, 1983, by one of the inventors herein, discloses and claims the basic concept of the present improved label transfer apparatus. However, further sepcific improvements thereof are necessary in order to extend the applicability of this basic concept.
Hence, there exists a need for further new improvements in an apparatus for transferring labels from a magazine into an open blow mold cavity, so that the apparatus will more readily overcome the disadvantages and limitations which existed in the prior art and have wider applications in the container industry.